Determination of the total oxygen demand of combustible materials in an aqueous dispersion has been useful in the field of pollution control. Water pollution control has been a long standing problem and is ever increasing in importance as pollution in various industries continues to grow in relation to natural water resources.
A known method for determining the total oxygen demand of combustible materials in an aqueous dispersion, which is described in the specification of U.S. Pat. No. 3,560,156 may be referred to as the "conventional method" of making this determination.
Because this conventional method is carried out by injection and combustion of a sample while a feed gas stream is flowing in a combustion zone at a high rate of several centimeters per second, this conventional method has various deficiencies. These include:
1. The entire sample must be injected into the combustion zone simultaneously and substantially instantaneously. When this condition is not satisfied, the peak of the measured value as indicated by the output electrical signal of the oxygen detector indicates a value that is lower than the actual value, or at least two peaks appear, or the peak loses its sharpness and widens considerably, and it is not possible to make precise measurements.
2. The contact time between the sample and the catalyst is very short. Therefore, the available combustion time is limited, which means that the unburned sample remains in the combustion zone. This makes it impossible to obtain precision measurements. Moreover, the catalyst or combustion conduit is unnecessarily contaminated.
3. In order to carry out combustion of the sample substantially instantaneously, the temperature of the combustion zone must be quite high, which not only requires increased manufacturing and running costs of the apparatus, but also shortens the lives of the combustion conduit and of the heating furnace as well.
Accordingly, a primary object of the present invention is to provide a method and apparatus for measuring the total oxygen demand which overcomes the deficiencies of conventional methods and drastically improves upon the conditions of simultaneous, momentary injection of the entire sample which has been an indispensable condition of the conventional method.
Another object of the present invention is to provide a method and an apparatus for measuring the total oxygen demand of combustible materials which method is capable of drastically increasing the combustion ratio (oxidation ratio) of the sample.
A third object of the present invention is to provide a method and apparatus for measuring the total oxygen demand of combustible materials, which method is capable of drastically reducing manufacturing and operating costs.
Other objects of the present invention will become clear from the following explanation.